The present invention relates to the selective sorting of objects moving along a conveying surface such that objects may be selectively diverted at both high conveying speeds and with small separation between objects.
The present invention relates to a conveying system where a conveying surface is provided along which objects to be sorted travel in a longitudinal direction. A diverting structure is placed across the conveying surface such that objects may be sorted into two groups, those that are undiverted and continue along the conveying surface, and those that are diverted transversly off the conveying surface, usually onto another conveying surface.
In high-speed situations, the time and distance spacing between objects is reduced and thus the time allowed for diversion is reduced.
A known diverter system utilizes a pusher plate mounted on a hydraulic ram and acting transversely of the conveying surface. This system is only useful for slow-speed sorting, since high speed sorting reduces the time allowed for diverting. Consequently, the speed of operation of the pusher plate must also increase, but this causes high-speed impact of the pusher plate on the object to be diverted, causing damage. A further disadvantage is that the pusher plate must pass from one side of the conveyor to the other, to divert the object, and return across the conveyor before a second object may be diverted. During this "dead time" of the return stroke, an object to be diverted may pass the diverting pusher plate and will not be diverted. Thus, a large spacing between objects is necessary, again slowing conveying and sorting speed.
A slightly more refined diverting system utilizes an endless chain situated in a slot below the conveying surface and mounted on two sprockets, one on each side of the conveying surface. The chain is angled at approximately 45.degree. to the conveying surface. Mounted on part of the chain are diverting members. The chain, in one position has these diverting members on its underside run, and not protruding above the conveying surface, allowing objects to pass, undiverted, over the conveying slot. Rotation of the sprockets will cause the diverting members to move to the upper run, presenting part of the diverting members above the conveying surface. An object travelling on the conveying surface shall contact these diverting members and, due to their angle to the longitudinal direction, shall be diverted sideways off the conveying surface. Again, since the diverting members are stationary, high-speed operation causes unacceptable damage and the mechanism also suffers from dead time, resulting in large spacing between objects.
Another prior art diverter system utilizes a chain which continuously rotates around two sprockets spaced under and across the conveying system. Both runs are beneath the conveying surface, and the sprockets are mounted on a framework which allows the sprockets to be raised such that the upper run is above conveying surface. The chain run is at an angle to the longitudinal direction. By choosing chain speed appropriate to the angle of the chain to the longitudinal direction and the conveying speed, each individual link shall have a speed in the longitudinal direction equal to the conveying speed. Thus, when diverting objects, the relative motion of the chain to object is a low-speed transverse one, reducing the impact and damage. While this system avoids damage through high speed impact, it still suffers "dead time" when the sprockets are being raised or lowered.
A further prior art system, described in Australian Patent No. 560857, utilizes a continuously moving chain rotating about sprockets at an angle to the conveying direction. Again, both runs are below the conveying surface but are fixed there. Mounted on the chain links are movable diverting members which, in a raised position, protrude above the conveying surface and divert objects as previously described, while in a lowered position do not protrude and do not divert.
This patent discloses two different movable diverter members. In the first system, the diverter members rotate in the plane of the chain, and thus a spacing between adjacent diverter members is required to allow for rotation from lowered to raised positions. This has the advantage of no dead time and low impact, but has the disadvantage of being unable to sort small objects due to the gaps between adjacent diverter members.
The second system utilizes diverter members sliding in a vertical plane parallel to the chain run between raised and lowered position. Each diverter member has a pin extending perpendicular to the plane of movement. In the raised position, the pin slides on the upper surface of a longitudinal bar. In the lowered position, the pin is below the bar. The lifter mechanism is at one end of this bar and selectively raises or lowers the diverter members. Since the pins must pass between upper and lower sides of the bar, there is a probability that a pin will not be moved sufficently and will jam on the end of the bar. This inhibits high speeds of operation.